The present invention relates to a production process of olefin polymer.
Known processes for producing olefin-base polymers, e.g., ethylene homopolymers and ethylene/α-olefin copolymers, include those carried out in the presence of a metallocene-base catalyst. These processes give polymers of higher mechanical strength, blocking capability and so forth than the conventional ones carried out in the presence of a Ziegler-Natta catalyst.
One of the known olefin production processes carried out in the presence of a metallocene-base catalyst comprises a step in which ethylene is preliminarily polymerized in the presence of a preliminary polymerization catalyst produced by bringing a metallocene-base complex, carrier and organoaluminum compound into contact with each other to produce a preliminary polymerization catalyst component; and a subsequent step in which ethylene and an α-olefin are copolymerized in a vapor-phase polymerization reactor in the presence of an organoaluminum compound of the similar species to that used in the preliminary polymerization step and the preliminary polymerization catalyst component. For example, ethylene and butene are preliminarily copolymerized in the presence of a preliminary polymerization catalyst produced by bringing into contact a metallocene-base complex, promoter carrier and triisobutyl aluminum to produce a preliminary polymerization catalyst component, and subsequently ethylene and 1-hexene are copolymerized in a vapor-phase polymerization reactor in the presence of trisiobutyl aluminum and the preliminary polymerization catalyst component (Patent Document 1).
Patent Document 1: JP-A-2005-97481